Successful manipulation of cable during cable-laying or cable-stringing operations requires some of the brute force and strength necessary in heavy construction and some of the accuracy and care necessary in sewing. Cables installed using tractor-driven implements are often of substantial size and weight while at the same time having many strands which are relatively fragile.
Because of this it is desirable to avoid unnecessary applications of force on the cable. And, to minimize the amount of human effort required for accurate cable installation it is desirable that the cable-handling implements operate properly.
A significant part of cable-laying and cable-stringing operations involves unreeling of cable, usually as a vehicle moves along the path of cable installation. Cable typically is provided to cable installers on large reels which when full of cable weigh as much as thousands of pounds. Such reels have center holes through which a shaft (spindle) extends to support the reel during unreeling.
A wide variety of cable-installing equipment has been developed over the years. Some examples of the prior art devices are disclosed in U.S. Pat. Nos. 3,780,813 and 3,926,263.
Cable-installing equipment typically has reel-carrying apparatus which includes a carrier frame with frame arms along opposite ends of the reel, opposed cradles on the frame arms, and a shaft extending through the center hole and having shaft end portions held in the cradles to support the reel between the frame arms. While such apparatus of the prior art is adequate, a number of problems and shortcomings of such equipment are well known to those who utilize such equipment in the field.
One well known problem in cable-laying is that, unless special steps are taken by the equipment operators, cable which has been laid slides along the trench because unreeling is resisted too much. This problem is seen most often during laying of the first portions of a line and during the early turns of the reel. It is these times when resistance to unreeling is greatest due to reel weight and resistance to in-trench sliding is least because of the light weight of cable already laid.
These problems are often dealt with by operators finding some way to apply downward force on the cable to pin it against the ground and prevent unwanted sliding. This sometimes involves more than one man standing on the cable. This, of course, takes operators away from other needed tasks and represents an expensive inefficiency.
Significant resistance to unreeling is a problem not only because of unwanted cable sliding in a trench, but also because of the fact that excessive pulling exerts force on cable which can tend to damage it, that is, damage parts of it. Excessive pulling to unreel cable, and all the related difficulties, are a significant problem with implements of the prior art.
Because of such problems, smaller and lighter (less filled) reels may sometimes be preferred. This, of course, leads to the necessity of more frequent reel changes during extended cable-installation operations. Using larger reels which are completely filled is highly desirable.
Various steps have been taken in the prior art to minimize the above-noted problems. For example, operators often will apply grease along the length of the shaft which extends through the reel in order to reduce the unreeling friction. This is helpful, but is less than a satisfactory solution for a number of reasons. For example, grease is often quickly absorbed by the reel, necessitating regreasing. Furthermore, grease along the shaft can be troublesome to deal with when the shaft is removed from a used reel and inserted into an unused reel.
In other cases the aforementioned cradle for the ends of the shaft (spindle) has been made of a pair of spaced rollers. This facilitates turning of the shaft, as opposed to turning of the reel on a stationary, or relatively stationary, shaft. However, for a variety of reasons this has not been an adequate solution to the problems mentioned above. For one thing, the shaft ends are prone to fall off such rollers, particularly as the frame arms are rotated upwardly or downwardly along their arc of travel to lift or lower the reel.
While various solutions have been tried, there remains a need for an improved reel-carrying apparatus for cable installing equipment of the type with a carrier frame and a shaft supported by the frame for holding a reel of cable.